Field
Mechanical Engineering. Production of vegetable oils by raw material pressing or by extracting waste material (C11B 1/00).
Technical Background
The marked importance of palm oil as raw material in the manufacture of food products, personal care products and in the production of biodiesel, among others, has led the extraction process of the palm fruit to be subject of permanent research, and therefore diverse systems and processes for palm oil extraction are currently known in the state of the art.
In this manner, for instance, nowadays the called ‘conventional systems’ are known for the palm oil extraction, which are basically characterized in that:
The sterilization process is performed statically and with the whole fruit (formed by the rachis and the seeds) by deposit in rail wagons for introduction into the sterilizer, which requires large areas for handling this equipment.
Additionally, said static sterilization is characterized by involving water consumption in the range between 800 liters and 1000 liters per processed tonne, sterilization times between 60 and 70 minutes, and an intermediate step between the sterilization and digestion processes that consists in separating fruits from rachis, already sterilized in rotating drums that contain the rachis with high levels of oil impregnation and attached fruit, fact that undoubtedly represents a high percentage of oil loss and also becomes an element of environmental pollution.
Fruits that are sterilized and separated from the rachis should undergo a digestion process through mechanical stirring and steaming for about 20 minutes, the above with the purpose that the fruits recover the lost temperature during the phase of separation from the rachis.
Once digestion is completed, fruits are subjected to a process of conventional pressing, where the liquid phase is released with a high solid content and therefore it is necessary to use equipment having greater capacity for oil clarification and obtention. In turn, the solid phase resulting from the pressing process has high humidity (up to 40%) due to the filtering medium generated in the press by the mesocarp fibers whose size does not exceed 4 mm.
Finally, the use of conventional systems for palm oil extraction involves the presence of sludge in the final effluent, requiring the implementation of large pools for their treatment.
On the other hand, ‘dynamic systems and processes’ for palm oil extraction are also known in the state of the art, such as those disclosed in the Colombian Patent CO 09-100.228, and which are characterized in that:
There is a first step of cracking and threshing of the whole fresh fruit, after which the spikes and rachis from detached fruits containing oil to be extracted are separated. Unfortunately, said process drags a great amount of fruit that remains attached to the rachis, causing excessive oil leaks.
Spikes and chopped rachis are pressed without having been subjected to a sterilization process, with which fruit gums that affect quality of the oil are obtained, as well as fibers with high crude oil impregnation whose acidification is evident and detrimental for the extra oil obtained. Additionally, pressing the fiber separately increases energy and equipment requirements, while vegetable fibers are exposed to fast putrefaction as a result of exposure to the environment.
The process of sterilization of the detached fruits containing the oil to extract is carried out by sterilizer equipment comprising inlet and discharge of the product valves with double gates for continuous sterilization, design that leads to serious issues due to the low capacity of processing of oil palm fruit.
The stirring system inside the sterilizers does not allow optimal stirring of the product because it uses a continuous helix with some agitation blades simply moving the product from the inlet towards the outlet of the sterilizer, but failing to produce a complete digestion of the product resulting in an optimal dynamic sterilization process.
Considering the above, it is evident that there is a need in the state of the art for developing a system and a process for palm oil extraction allowing to overcome the technical problems encountered with the use of the currently known systems and methods, redesigning the system equipment and the steps of the extraction process to reduce process costs and increase the quality of the obtained product.